Signal strength indications accessible when connected in infrastructure mode will be unavailable to you in ad-hoc mode. Therefore, you will face some difficulty whenever re-positioning an ad-hoc device to achieve a better signal.

You should expect that WiFi devices supporting 54 Mbps or higher in infrastructure mode, will drop back to a maximum of 11 Mbps when changed to ad-hoc mode. Ad-hoc mode should generally be viewed as "slower" than infrastructure mode for this reason.